The invention relates broadly to reducing the water content of an aqueous sulfuric acid solution. More specifically, the invention relates to the regeneration of aqueous sulfuric acid of any desired concentration by means of electrolysis.
The problem of satisfactorily, efficiently and economically removing water from aqueous sulfuric acid containing less than about 50 per cent by weight water has been a long standing enigma. Evaporation of the water by distillation requires the use of high temperatures at which the hot concentrated acid is highly corrosive and is difficult to contain.
Moreover, previous attempts to concentrate aqueous sulfuric acid by electrolysis invariably have demonstrated that in addition to the production of hydrogen gas and oxygen gas thereby decomposing and removing water from the acid, cathodic reduction of the acid itself occurs forming solid elemental sulfur which deposits on the cathode and disperses into the acid. Such sulfuric acid, contaminated with solid sulfur, is generally unsuitable for use in industrial applications. This has made the electrolytic method appear to be unsatisfactory for providing high concentrations of sulfuric acid on a commercial basis.